The Association of Upper-Body Kinematics and Earned Run Average of National Collegiate Athletic Association Division I Softball Pitchers.

ABSTRACT: Friesen, KB, Barfield, JW, Murrah, WM, Dugas, JR, Andrews, JR, and Oliver, GD. The association of upper-body kinematics and earned run average of national collegiate athletic association Division I softball pitchers. J Strength Cond Res 35(11): 3145-3150, 2021-Although recent literature has increased examination of the association of injury and biomechanics, there remains a lack of evidence supporting optimal windmill pitch mechanics. Therefore, the purpose of this study was to investigate trunk and pitching arm kinematics and their association with performance outcome: earned run average (ERA), in collegiate softball pitchers. Twenty-three NCAA Division I collegiate softball pitchers (20.14 ± 1.07 years; 173.93 ± 6.68 cm; and 85.79 ± 11.06 kg) performed 3 maximal effort rise ball pitches to a catcher located at a distance of 43 ft. (13.11 m). Kinematic data of the trunk and pitching arm were collected using an electromagnetic tracking system. A multiple regression analysis was performed at each pitch event: top of backswing, foot contact, ball release, and follow-through. The multiple regression at foot contact showed an overall statistically significant regression equation (F6, 16 = 3.7, p = 0.017) and explained approximately 42% of the variance in ERA (R = 0.579, Adj. R2 = 0.421). Results revealed that those pitchers who had greater trunk (SE = 0.018, t = -2.5, p = 0.023) and elbow flexion (SE = 0.006, t = -4.2, p = 0.001) at the event of foot contact had lower ERAs. This study supported previous research on the importance of trunk and elbow angle at front foot contact on rise ball pitch performance. These key technique points and the importance of elbow flexors should be explored in future research and potentially visually attended to by coaches and strength professionals.

Association of Upper Extremity Pain With Softball Pitching Kinematics and Kinetics.

BACKGROUND: There is a paucity of research regarding the relationship between fastpitch softball pitching mechanics and reported pain. Thus, understanding the pitching mechanics of athletes pitching with upper extremity pain and those pain free is paramount. PURPOSE: To examine lower extremity pitching mechanics, upper extremity kinetics, and upper extremity pain in National Collegiate Athletic Association (NCAA) Division I female softball pitchers. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 37 NCAA Division I female softball pitchers (mean age, 19.84 ± 1.28 years; mean height, 173.67 ± 7.77 cm; mean weight, 78.98 ± 12.40 kg) from across the United States were recruited to participate. Participants were divided into 2 groups: upper extremity pain (n = 13; mean age, 19.69 ± 1.18 years; mean height, 172.60 ± 11.49 cm; mean weight, 86.75 ± 13.02 kg) and pain free (n = 24; mean age, 19.91 ± 1.35 years; mean height, 174.26 ± 4.96 cm; mean weight, 74.78 ± 9.97 kg). An electromagnetic tracking system was used to obtain kinematic and kinetic data during the riseball softball pitch. RESULTS: At foot contact (F 3,33 = 7.01, P = .001), backward elimination regression revealed that stride length, trunk rotation, and center of mass (COM) significantly explained about 33% of variance with softball pitchers experiencing upper extremity pain (adjusted R 2 = 0.33). CONCLUSION: At foot contact, the kinematic variables of increased trunk rotation toward the pitching arm side, increased stride length, and a posteriorly shifted COM were associated with upper extremity pain in collegiate softball pitchers. Variables early in the pitching motion that do not set a working and constructive proximal kinetic chain foundation for the rest of the pitch to follow could be associated with breakdowns more distal in the kinetic chain, possibly increasing the susceptibility to upper extremity pain. CLINICAL RELEVANCE: The identification of pitching mechanics associated with pain allows clinicians to develop exercises to avoid such mechanics. Avoiding mechanics associated with pain may help reduce the prevalence of pain in windmill softball pitchers as well as help coaches incorporate quantitative biomechanics into their instruction.

A hypermobile Wrisberg variant lateral discoid meniscus seen on MRI.

The discoid menisci is a common abnormalitiy of the knee seen by pediatric and general orthopaedists. This aberration of the fibrocartilaginous meniscus can occur medially, but is most common on the lateral side. Because of unusual biomechanical stresses, all discoid menisci are at increased risk for meniscal tears. Types I and II variations have a disc-shaped meniscus, which cover more of the tibial plateau than normal and may be of increased thickness. Both have normal attachment to the tibial plateau and do not require treatment when asymptomatic. The Wrisberg or Type III variant may not be abnormal in shape. It lacks posterior attachment to the tibia resulting in a hypermobile meniscus. The knee may snap or pop when flexed and lock in extension; pain is a common presenting complaint. Radiographs can aid diagnosis, but frequently are not definitive. Identification of discoid menisci and associated meniscal tears can be accomplished with magnetic resonance imaging. Where no tear exists and the meniscus is normal in shape, diagnosis may be more difficult. Presented here is a case of a discoid lateral meniscus not observable on initial magnetic resonance images but visible on magnetic resonance images taken while the affected knee was extended in the locked position.

Differences in the ultimate strength of the biceps anchor and the generation of type II superior labral anterior posterior lesions in a cadaveric model.

BACKGROUND: The pathogenesis of superior labral anterior posterior lesions remains controversial. HYPOTHESIS: The biceps anchor is more vulnerable to loading with a posterior vector as opposed to an in-line pull. STUDY DESIGN: Controlled laboratory study. METHODS: Eight pairs of cadaveric shoulders were dissected, and the biceps tendon was loaded to failure in 1 of 2 loading patterns. Loading pattern A was meant to simulate the eccentric load of the biceps in the deceleration phase of throwing; loading pattern B was meant to simulate the posterior biceps load of the late cocking phase. RESULTS: The biceps anchor demonstrated significantly increased ultimate strength with in-line loading (group A, 508 N) as opposed to posterior loading (group B, 262 N, P < .001). All group B specimens failed at the biceps anchor, resulting in a type II superior labral anterior posterior lesion. Specimens in group A did not create a superior labral anterior posterior lesion. CONCLUSIONS: Direction of biceps loading resulted in significant differences in the ultimate strength of the biceps anchor and the generation of superior labral anterior posterior lesions. The biceps anchor was significantly weaker when loaded with a posterior vector. RELEVANCE: The superior labrum may be most vulnerable to injury in late cocking. The reproducible generation of type II superior labral anterior posterior lesions may have applications as a biomechanical model.